About 20 years ago when I was dealing with a lot of neck pain, I very nearly overdosed accidentally. It was a combination of prescription and OTC NSAIDs, muscle relaxers, and Diet Coke, which seemed to kick off the whole reaction, as I had taken the other meds over the previous 4 hours. There could have been Benadryl or Claritin in there as well, I don’t recall. Suddenly I couldn’t walk, was slurring my words, and could feel something really weird happening to my body. I called poison control. While I was on the phone with him, I started barfing, thank goodness. He called me again an hour later to make sure I was okay.
That’s why I said it must have been a lot of pills, because I’m sure I’ve hit on that exact combo many times during my spring allergy season.